New data establish Arimidex as superior to tamoxifen in
preventing breast cancer recurrence

December 8, 2004 -- New data, from the landmark ATAC (Arimidex',
Tamoxifen, Alone or in Combination) trial, were presented at the
San Antonio Breast Cancer Symposium, in Texas. These definitive
data show that in postmenopausal women with hormone sensitive,
early breast cancer, AstraZeneca's treatment, Arimidex
(anastrozole), reduces the risk of breast cancer returning by an
additional 26 per cent over and above the 50 per cent reduction in
risk already offered by tamoxifen. These data also conclude that
Arimidex' is associated with fewer life threatening side effects
than those seen with tamoxifen, particularly blood clots, stroke
and cancer of the womb lining.

The greatest fear for women who have been treated for early
stage breast cancer is to have their cancer return. Experts agree
that the first five years following primary surgery is when women
are at greatest risk of their disease returning.

"It is critical that women get the best treatment option
available to them at the earliest opportunity after diagnosis to
minimise the risk of recurrence," said Professor John Forbes of
Newcastle Mater Misericordiae Hospital, Australia.

Data from the ATAC trial now conclusively demonstrate that
Arimidex provides women with even greater protection than tamoxifen
by reducing the risk of breast cancer recurrence by over half as
much again. As a result, more women can live cancer free. A
reduction in this risk of recurrence is associated with an
improvement in overall survival; Arimidex offers women the best
possible chance to stay alive and cancer free.

Professor John Forbes added, "Quite simply, if breast cancer
does not return, women will not die from it. With tamoxifen, many
women have had to live with the risk that their breast cancer could
come back, even before they have completed their course of
treatment. Now, for the first time in 30 years, we have a drug that
is better than tamoxifen to fight breast cancer - anastrozole."

Arimidex is the only drug of its type to have extensive safety
data with over five years of clinical experience in early breast
cancer. Tolerability is of primary concern for women with early
breast cancer and for clinicians treating them. These data show
that Arimidex is better tolerated than tamoxifen, both for serious
life threatening side effects and other side effects affecting
quality of life. Women taking Arimidex in the ATAC trial
experienced more fractures and joint pain than those receiving
tamoxifen, which is known to have a positive effect on bone mineral
density. However, the side effects of Arimidex are considered more
predictable and manageable than some of the serious side effects
commonly associated with tamoxifen. Additionally, as a result of
the better tolerability profile, women on Arimidex were more likely
to stay on therapy for longer than those on tamoxifen.

The vast majority of patients in the ATAC trial have completed
five years of treatment and these data are now considered
conclusive. Breast cancer specialists believe that anastrozole
should replace tamoxifen as the preferred initial hormonal
treatment, in order to provide women with the best possible chance
of staying free of their disease.

About the ATAC trial

The ATAC trial is the largest and longest running early breast
cancer treatment study. The trial reports data from over 9,300
postmenopausal women with early breast cancer who took either
anastrozole or tamoxifen once per day for five years following
their initial breast cancer surgery. This latest analysis compares
the two groups of women once the majority had completed their
treatment. The new data show that anastrozole reduces the risk of
all forms of breast cancer recurrence by an additional 26 per cent
over and above that offered by tamoxifen. Furthermore, anastrozole
provides an additional 16 per cent reduction in the risk of the
disease spreading to other parts of the body, compared to
tamoxifen.

The ATAC trial compares five years of treatment with tamoxifen
to five years of treatment with anastrozole, in women newly
diagnosed with early breast cancer. Eighty-four per cent of
patients in the trial had tumours which are known to respond to
hormonal treatment.

Drugs.com provides accurate and independent information on more than 24,000 prescription drugs, over-the-counter medicines and natural products. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment.